JPH06109133A - One-way clutch friction preventing device of automatic transmission - Google Patents

Abstract

PURPOSE:To eliminate the tightening delay of a friction element in the downshift speed change where the friction element released for preventing the friction of a one-way clutch is retightened. CONSTITUTION:A valve 16 is in a descending position at the fourth speed where a band brake B/B is tightened by a fourth speed selecting pressure P4, and a valve 18 can be set to the lowered position by turning OFF a solenoid valve C. This constitution allows the working pressure of a clutch F/C to be drained, and the release prevents the friction of a one-way clutch FO/C related thereto. An orifice 18c supplements the fluid of a circuit 19 to a circuit 23, and leaves the residual pressure in the clutch F/C. Thus, the tightening of the clutch F/C which is required for the 4 3 downshift speed change is rapidly executed, and the tightening delay is avoided and the racing of the engine can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing friction when a one-way clutch provided in a power transmission system of an automatic transmission is released.

[0002]

2. Description of the Related Art An automatic transmission selects a corresponding shift speed by selectively hydraulically operating (engaging) various friction elements (friction clutches and friction brakes), and changes the operating friction element to shift to another shift speed. Configure to do.

When performing an upshift shift from a low speed stage to a high speed stage, power transmission in the low speed stage is performed via a one-way clutch so that the shift to the high speed stage is completed by releasing the one-way clutch. However, many automatic transmissions employ this method today.

[0004] The applicant of the present invention is currently developing and using
N Maxima New Car Manual, "Introduction of Changes to J30 Type Cars" 1
The automatic transmission described in August 991 (FOO7671) is no exception. In this automatic transmission, the forward one-way clutch corresponds to the above one-way clutch, and the forward one-way clutch is the first
The gears are engaged in the first to third speeds to contribute to power transmission, and are released when shifting to the fourth speed, which is performed when the band brake is additionally operated in the third speed state, and the shifting can be smoothly performed. .

However, at the fourth speed, the forward one-way clutch remains connected to the rotating members that rotate the inner and outer races separately, so that the one-way clutch flick shock due to the relative rotation between the inner and outer races can be avoided. However, the power loss increases correspondingly, resulting in deterioration of fuel efficiency.

To solve this problem, the present applicant has previously
According to Japanese Patent Application No. 4-50734, since the friction element (forward clutch) related to the one-way clutch does not participate in power transmission in the fourth speed, the control valve for draining the operating pressure of the element is changed to open it. A device has been proposed which is added to a control hydraulic circuit to prevent the friction of the one-way clutch.

[0007]

However, if a measure for releasing the friction element for selecting the low speed stage at the high speed stage (the fourth speed) is taken in this way, the friction element is brought down to the low speed stage to be engaged. At the time of shift shift, the cylinder capacity of the element is large because it is for a low speed stage, and an accumulator is provided in the operating pressure circuit of the element as a countermeasure against shift shock, so that the engagement of the element tends to be delayed, The following problems occur.

That is, the automatic transmission in the invention of the above-mentioned prior application will be described in detail. As shown by the broken line in FIG. 5, the forward clutch pressure P from the instant t ₁ when a downshift command from the 4th speed to the 3rd speed is issued. _{Although the F / C} increases, the forward clutch cannot avoid the engagement delay due to the above reason, and the automatic transmission is momentarily set to the neutral state during the gear shift. By the way, downshifting usually occurs during power-on running when the engine accelerator pedal is depressed,
At this time, the engine runs idle just before the forward clutch engagement start instant t ₂ as shown by the broken line in FIG. 5, causing not only a shift delay but also a large shift shock associated with the idle running.

According to the present invention, the residual pressure is left in the friction element (forward clutch) for selecting the low speed stage even during the release for the purpose of preventing the one-way clutch friction, so that the friction element is immediately before being engaged with the working fluid. It is an object of the present invention to eliminate the above-mentioned problem by configuring the one-way clutch friction prevention device so that the friction element can be quickly engaged during downshifting by maintaining the state of.

[0010]

To this end, the one-way clutch friction prevention device of the present invention engages another friction element in a low speed selected state in which power is transmitted through the one-way clutch by engaging a certain friction element. At this time, the one-way clutch is released so that the gear can be shifted to the high speed stage. At this high speed stage, the operating pressure of the certain friction element is drained by the control valve to prevent the friction of the one-way clutch. The automatic transmission is provided with residual pressure means for replenishing the certain friction element with a working fluid during draining of the operating pressure of the certain friction element by the control valve to apply a residual pressure to the certain friction element. It is characterized by the point that it was composed.

In the above structure, it is advantageous that the residual pressure means is built in the control valve.

[0012]

When the automatic transmission is engaged with a certain friction element, the automatic transmission is brought into a low speed stage selection state in which power is transmitted through the one-way clutch. When the other friction element is engaged in this state, the one-way clutch is disengaged to shift to the high speed stage. In this high speed stage, the control valve drains the operating pressure of the certain friction element associated with the one-way clutch to release the friction element. Therefore, at a high speed, this friction element disconnects the one-way clutch from the corresponding rotating member, and the forced relative rotation of the one-way clutch inner and outer races is avoided, and the friction of the one-way clutch can be prevented.

By the way, during draining of the working pressure of the certain friction element by the control valve, the residual pressure means replenishes the certain friction element with working fluid to apply the residual pressure to this friction element. Therefore, when the friction element is released to prevent friction of the one-way clutch, the 雛 also performs the above-mentioned friction prevention action in a state immediately before the engagement filled with the working fluid, and the friction element should be engaged. The friction element does not cause an engagement delay during downshifting, and it is possible to avoid a shift delay associated with this engagement delay, an engine idling, and a large gearshift shock associated with engine idling.

In the second aspect of the invention, the structure in which the residual pressure means is built in the control valve can reduce the number of parts and simplify the structure, which is very advantageous in terms of cost.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a power transmission train and an engagement logic table of various friction elements of an automatic transmission to which the one-way clutch friction prevention device of the present invention is applied. This transmission train is the same as that described in the above-mentioned document, and includes an input shaft 2 to which rotational power from the engine crankshaft is transmitted via a torque converter 1 and an output shaft 3 coaxially with the input shaft 2, and these input and output shafts The first planetary gear set 4 and the second planetary gear set 5 coaxially arranged, and various friction elements described later are included.

The first planetary gear set 4 is an ordinary simple planetary gear set including a sun gear 4S, a ring gear 4R, a pinion 4P meshing with these, and a carrier 4C rotatably supporting the pinion 4P, and the second planetary gear set 5 is also included. Sun gear 5
A simple planetary gear set including S, a ring gear 5R, a pinion 5P and a carrier 5C.

Next, various friction elements that control the shift control will be described. The carrier 4C can be appropriately connected to the input shaft 2 via the high clutch H / C, the sun gear 4S can be appropriately fixed by the band brake B / B, and can be appropriately connected to the input shaft 2 by the reverse clutch R / C. To do. The carrier 4C can be further appropriately fixed by a multi-plate low reverse brake LR / B and prevents reverse rotation (rotation in the direction opposite to the engine) via the low one-way clutch LO / C. The ring gear 4R is integrally connected to the carrier 5C and drivingly connected to the output shaft 3, and the sun gear 5S is connected to the input shaft 2. Ring gear 5R is overrun clutch OR / C
In addition to being able to be appropriately coupled to the carrier 4C via the, the carrier is correlated with the carrier 4C via the forward one-way clutch FO / C and the forward clutch F / C. Forward one-way clutch FO / C is forward clutch F
In the coupled state of / C, the ring gear 5R is coupled to the carrier 4C in the reverse rotation direction (direction opposite to the engine rotation).

High clutch H / C, reverse clutch R
/ C, low reverse brake LR / B, overrun clutch OR / C, and forward clutch F / C, respectively.
The band brake B / B is actuated by the supply of hydraulic pressure to perform the appropriate coupling and fixing, but the band brake B / B is particularly designed as shown in the table of FIG. 1 for the second speed servo apply chamber 2A, the third speed servo release chamber 3R and the fourth speed. It has a servo apply chamber 4A, which is opened in a normal state and is fastened by supplying pressure only to the chamber 2A. It is opened when pressure is supplied to the chamber 3R in addition to the chamber 2A, and to the chamber 4A in addition to the chambers 2A and 3R. It shall be fastened when supplying pressure.

The power transmission train of FIG. 1 includes friction elements B / B and H.
/ C, F / C, OR / C, LR / B, R / C are operated in various combinations (shown by circles) as shown in the table of the figure, so that the friction elements FO / C, LO / In combination with the appropriate operation (engagement) of C, the rotational states of the elements constituting the planetary gear sets 4, 5 are changed, and thereby the rotational speed ratio of the output shaft 3 to the rotational speed of the input shaft 2 is changed to move forward. It is possible to obtain the gear position of the fourth reverse and the first speed. 1 also indicates the operation (hydraulic inflow), the Δ indicates a friction element to be operated when engine braking is required. And
While the overrun clutch OR / C is operating as indicated by the mark Δ, the forward one-way clutch FO / C juxtaposed to this is kept unreleasable to enable engine braking, and the low reverse brake LR / B operates. It goes without saying that the low one-way clutch LO / C juxtaposed to this is kept non-releasable while the engine is being braked during this time.

Further, in the table of FIG. 1, the forward clutch F /
The dotted circle in C indicates that this clutch has been conventionally engaged for the sake of convenience of the shift control hydraulic circuit although it does not participate in power transmission at the fourth speed. In this case, at the 4th speed, the outer race of the forward one-way clutch FO / C is driven at the same speed as the input rotation, and there is relative rotation between the outer race and the inner race that is being rotated at an increased speed. / C friction causes deterioration of fuel efficiency.

Therefore, in the present embodiment, the one-way clutch FO / C is made by deactivating (releasing) the forward clutch F / C by the drain of the operating pressure at the fourth speed.
It allows the outer race of the car to rotate following the inner race and prevents the friction of the one-way clutch to improve fuel efficiency. For this purpose, the shift control hydraulic circuit for the power train of FIG. 1 is constructed as shown in FIG. However, this circuit is basically the same as the shift control hydraulic circuit described in the above document, and FIG. 2 shows only the portion related to the present invention.

Reference numeral 11 denotes a regulator valve, which regulates the hydraulic oil from the oil pump 12 to a predetermined line pressure P _L by a well-known action, and outputs it to the circuit 13 so as to use it as all the source pressures of the automatic transmission. To do. This line pressure is a manual valve 14,
This is supplied to the pilot valve 15 and the switching valve 16, and the pilot valve 15 reduces the line pressure P _L to a constant pilot pressure P _P , which is controlled by the circuit 17 to the forward clutch control valve 18, the shift solenoids A and B, and the over solenoid. Supply to the run clutch solenoid C.

The manual valve 14 is manually operated according to the traveling mode desired by the driver, and is set to P when the vehicle is parked (stopped).
(N) When the range is set, the line pressure of the circuit 13 is not supplied to any output circuit, and the entire line is drained. Manual valve 14
Outputs the line pressure of the circuit 13 as the D range pressure P _D to the circuit 19 when the automatic shift running is set to the D range and drains all the other output circuits to request the second speed engine brake running. The line pressure of circuit 13 to circuit 20
Also outputs as 2 range pressure P ₂ and drains the other output circuit to make it to 1 range in order to drive the first speed engine brake. The line pressure of circuit 13 is also supplied to circuit 21 as 1 range pressure P ₁
, And the other output circuit is drained.
Further, the manual valve 14 outputs the line pressure of the circuit 13 as the R range pressure to the circuit 22 when the reverse travel is desired and the R range is set, and all the other output circuits are drained.

On the other hand, the D range pressure circuit 19
Switch control valve 18, which is a spool 18_a
Connect the circuit 23 to the D range pressure circuit 19 at the position
Le 18 _aAt the lower position in the figure, switch circuit 23 to 2 range pressure circuit 20.
A replacement connection shall be made. And valve 18 is spool 18_a
Pilot pressure P of circuit 17 at the upper end of_PAlways acted, reverse
Spring 18_bAnd the pressure from the circuit 24 is acted on by the circuit
Spool 18 depending on the presence or absence of pressure from 24_aAt the position shown
Stroke control shall be performed with respect to the lowered position.

The spool 18a further has an orifice 18c.
3, the orifice 18c is blocked when the spool 18a is stroked to the left half position in the figure by the pressure from the circuit 24, as shown in FIG. When a stroke is made to the right half position in the figure, the circuit is opened and the circuits 19 and 23 are restrictedly communicated. Although the spool 18a communicates between the circuits 20 and 23 at the latter position as described above, the degree of communication is smaller than the opening degree of the orifice 18c in view of the operation described later.

On the other hand, the D range pressure circuit 19 is connected to the switching valve 16 and the overrun clutch control valve 25, and is also connected to the D range shift control oil passage (not shown), and the shift solenoids A and B are shown in FIG. By turning on and off, the hydraulic pressure supply logic indicated by a circle in the table of FIG. 1 is achieved, and the first speed to the fourth speed can be automatically selected. However, when the shift solenoids A and B are ON, the pilot pressure P _P of the circuit 17
It outputs to 26, 27 as shift signal pressure, and circuit 26, 27 at the time of OFF
Shall be drained.

The switching valve 16 receives the fourth speed selective pressure P ₄ of the circuit 28 on the upper end of the spool 16 _a , and the spring 16 _b and the circuit 16 in the opposite direction.
The two range pressure P ₂ from 20 is actuated to connect the circuit 24 from the forward clutch control valve 18 to the line pressure circuit 13 and to control the circuit 29 from the overrun clutch control valve 25 at the illustrated position of the spool 16 _a. through the circuit 30 from the solenoid C, and the circuit 30 the circuits 24 in the lowered position of the spool 16 _a, also the circuit 29 D-range pressure circuit
Switch to 19 and connect.

The 4th speed selection pressure P ₄ of the circuit 28 is a pressure generated when the 4th speed is to be selected by the above-mentioned automatic shifting, and this pressure is a band when the overrun clutch control valve 25 connects the circuit 31 to the circuit 28. The fourth speed can be selected by being supplied to the fourth speed servo apply chamber 4A of the brake B / B. The control valve control solenoid C is the same as the shift solenoids A and B, and the pilot pressure of the circuit 17 is output to the circuit 30 when it is ON, and this circuit 30 is drained when it is OFF.

The overrun clutch control valve 25 has _a spring 24a at the upper end of the spool and one range pressure P _{1 of the} circuit 21.
Is act, is acted the pressure of the circuit 29 in the opposite direction, through the circuit 28 in the lowered position shown in drain port 25 _c, also the circuit 32 from overrunning clutch OR / C to the D range pressure circuit 19, increases circuit 28, 32 is assumed to be connected is switched to the respective circuits 31 and drain port 25 _c in position.

The operation of the above embodiment will be described below. Manu
During automatic shifting with the Al valve 14 in the D range, shift shift
The ON / OFF states of theoids A and B shown in FIG.
The first to fourth speeds are selected according to the logic shown in the table. 1st speed
To the 4th speed selection pressure P in the 3rd speed_Four Does not occur and the switching valve 16
Spool 16_aTo the ascending position shown and connect circuits 24 and 29 to
I am familiar with 13, 30. Therefore, the line pressure is supplied to the circuit 24.
And the forward clutch control valve 18 spools
18 _aTo the raised position shown in FIG. By this D
The D range pressure output to the circuit 19 in the range is valve 18, circuit 23
Through the forward clutch F / C, and
Keeping the condition, it is possible to select the first to third speeds.

When the driving condition in which the engine brake is required in the first to third speeds is reached, the computer judges this and turns off the solenoid C to drain the circuit 30. Therefore, the circuit 29 connected to the circuit 30 is also drained, and the overrun clutch control valve 25 connects the circuit 32 to the D range pressure circuit 19 to engage the overrun clutch OR / C to realize automatic engine braking. .
Then, while engine braking is not required, the pilot pressure is supplied to the circuit 30 by turning on the solenoid C, and the pilot pressure is supplied to the valve 25 via the circuit 29. Therefore, the valve 25 drains the overrun clutch OR / C. Circuit 28 is connected to circuit 31 as well as open to port 25 _c .

Therefore, when the fourth speed selective pressure P ₄ is generated in the circuit 31, it is transmitted from the circuit 28 to the chamber 4 of the band brake B / B.
When the driver reaches A, the fourth speed can be selected by engaging the band brake.

By the way, in this fourth speed selection state, the fourth speed selection pressure P ₄ acts on the upper end of the switching valve 16 and the two range pressure P ₂ acting on the lower end does not exist in the D range. The switching valve 16 is in the lowered position, switching the circuits 24, 29 to the circuits 30, 19 respectively. Forward clutch control valve by solenoid C by connecting circuits 24 and 30
18 can be controlled, and the overrun clutch control valve 25 is held in the raised position by the communication of the circuits 29 and 19.
This enables the band brake B / B to be fastened and held (the fourth speed is selectively held) by the speed P ₄ and the switching valve 16 to be held in the lowered position.

Here, in the fourth speed selection state, the computer turns off the solenoid C. As a result, the forward clutch control valve 18 is moved to the lowered position (right half position in FIG. 3) by the drain of the circuit 30, and thus the drain of the circuit 24, and the circuit 23 is switched and connected to the two-range pressure circuit 20.
By the way, in the D range, since the two-range pressure circuit 20 is drained, the operating pressure of the forward clutch F / C is drained therethrough and can be released. As described above, in the fourth speed, the forward clutch F / C that does not contribute to power transmission is deactivated, and it is possible to prevent the friction of the forward one-way clutch FO / C described above with reference to FIG. 1 and improve fuel efficiency.

During this period, the forward clutch control valve 18 drains the forward clutch engagement pressure P _{F / C} from the circuit 23 from the circuit 20, as is apparent from FIG. The circuit 23 is replenished with the D range pressure P _D via the orifice 18c, and the forward clutch engagement pressure P of this circuit 23 is increased.
_{The F / C} does not become 0, and the forward clutch F / C is shown in FIG.
The residual pressure of about Pi shown in (1) remains, and this clutch is maintained in the state immediately before the engagement in which the working fluid is filled. Therefore, at the time of the 4 → 3 downshift shift performed by engaging the forward clutch F / C, the following operational effects can be obtained.

In this 4 → 3 downshift, the operation shown in FIG.
As is apparent from the above, the shift solenoid A is turned off, and the fourth speed selective pressure P ₄ of the circuit 31 is eliminated. As a result, the switching valve 16 is switched to the position shown in FIG. 2 so that the circuits 13, 24 and 29, 30 are in communication with each other. Circuit 1
The forward clutch control valve 18 is also switched to the position of FIG. 2 by the communication between 3 and 24, and the forward clutch engaging pressure P _{F / C} from the circuit 23 is increased as shown by the solid line in FIG. By engaging C, the shift is completed as prescribed.

By the way, as described above, the forward clutch is
The engagement pressure P even when the F / C is released. _{F / C}Is not set to 0,
Immediately before engagement, with residual pressure Pi filled with working fluid
Therefore, the forward clutch engagement pressure P_{F / C}
Shows a rapid rise and forward movement as shown by the solid line in Fig. 5.
As shown in the figure, there is no delay in the engagement of the latch F / C.
It is also clear from the trend of changes in engine speed indicated by the solid line
In order to prevent the engine from running dry,
Can be prevented from occurring.

[0038]

As described above, according to the one-way clutch friction preventing device of the present invention, the one-way clutch (in the illustrated example, the forward one-way clutch) is engaged by engaging a certain friction element (the forward clutch F / C in the illustrated example). The one-way clutch is released when another friction element (band brake B / B in the illustrated example) is engaged in a low speed stage (third speed in the illustrated example) selected state in which power is transmitted via the clutch FO / C). High speed (in the example shown,
(4th speed), the operating pressure of the certain friction element is controlled by the control valve (in the illustrated example, at this high speed).
In an automatic transmission in which a forward clutch control valve (18) drains to prevent friction of the one-way clutch, a hydraulic fluid is applied to a certain friction element during draining of the operating pressure of the certain friction element by the control valve. And a residual pressure means (orifice 18c in the illustrated example) for applying a residual pressure to the certain friction element is provided. The friction element that is to be engaged is engaged from the state immediately before the engagement in which the working fluid is filled with the residual pressure.
This engagement can be completed promptly, and it is possible to eliminate the inconvenience of causing the engine to run dry during the gear shift and causing a large shift shock due to the running.

According to the present invention as set forth in claim 2, since the residual pressure means is built in the control valve, the number of parts can be reduced and the structure can be simplified, which is very advantageous in terms of cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a power transmission train of an automatic transmission to which a one-way clutch friction prevention device according to an embodiment of the present invention is applied, together with an engagement logic table of various friction elements.

FIG. 2 is a circuit diagram showing only a portion related to the present invention of a shift control hydraulic circuit of the transmission train.

FIG. 3 is a detailed enlarged sectional view of a forward clutch control valve in the shift control hydraulic circuit.

FIG. 4 is a logical table showing a relationship between ON / OFF of a shift solenoid and a selected shift stage in the same shift control hydraulic circuit.

FIG. 5 is a time-series time chart showing the operation of the shift control hydraulic circuit in comparison with that of a conventional device.

[Explanation of symbols]

1 torque converter 2 input shaft 3 output shaft 4 first planetary gear set 5 second planetary gear set F / C forward clutch (a certain friction element) B / B band brake (other friction element) FO / C forward one-way clutch ( One-way clutch) H / C High clutch OR / C Overrun clutch R / C Reverse clutch LR / B Low reverse brake A Shift solenoid B Shift solenoid C Control valve control solenoid 11 Regulator valve 12 Oil pump 14 Manual valve 15 Pilot valve 16 Switching Valve 18 Forward clutch control valve (control valve) 18 _C Orifice (residual pressure means) 25 Overrun clutch control valve

Claims (2)

[Claims] 1. When one friction element is engaged and another friction element is engaged in a low speed stage selection state in which power is transmitted through a one-way clutch, the one-way clutch can be released to shift to a high speed stage. In the automatic transmission capable of preventing the friction of the one-way clutch by draining the operating pressure of the certain friction element by the control valve at this high speed stage, the operating pressure of the certain friction element by the control valve is changed. A one-way clutch friction prevention device for an automatic transmission, comprising: a residual pressure means for replenishing a working fluid to the certain friction element in a drain to apply a residual pressure to the certain friction element. 2. The one-way clutch friction prevention device for an automatic transmission according to claim 1, wherein the residual pressure means is built in the control valve.